Grizzly cameras aimed at understanding how bears make it through the North Slope winter
On Alaska’s remote North Slope, where grizzlies spend much of the year in hibernation, a research team is using collar cameras to capture what the bears do when people are not there. Washington State University doctoral student Ellery Vincent and Alaska Department of Fish and Game biologist Jordan Pruszenski said the project has outfitted 12 of about 200 grizzlies that roam the frigid, treeless terrain near the Arctic Ocean.
Vincent said the seasonal timing is crucial to survival, describing the bears’ feeding window after hibernation. “They really have a really short window to obtain enough food resources to pack on enough fat to survive that period,” Vincent said, adding that the team is focused on how the bears find food and what they choose to eat.
The researchers also said they are looking at whether the North Slope grizzlies hunt musk oxen. Pruszenski said there are about 300 musk ox on the North Slope, but that the grizzly population is not flourishing.
The first year’s footage, researchers said, shows that after the bears emerge from hibernation they eat carcasses of caribou or musk ox that died over the winter. The videos then show the bears attacking caribou calves, and as the tundra greens up the bears shift toward vegetation, including blueberries and soapberries, also called buffaloberries.
Vincent said the cameras have also provided a sense of how long the bears spend on particular activities, even though the recordings are brief. “One thing that’s really nice about these bears is that when they’re foraging on a particular food they tend to do that one thing for a long period of time, so these bears will spend pretty much their entire day eating, so the chances of us actually seeing what they’re doing are pretty high,” Vincent said.
The project’s fieldwork relied on helicopters and tranquilizer darts to fit the collars. Researchers tracked the bears through snow by helicopter last May, then Pruszenski fired darts from the air while Vincent tracked injection times and helped determine when it was safe for the team to approach. The team placed collars loosely enough for the bears to grow into them as they gained weight, but tight enough to keep them from falling off as bears moved through their rough-and-tumble routines.
Researchers darted the bears again in August to replace the collars and in September to download data, and they also measured weight gain and body fat. When the collar cameras came off, Alaska’s wildlife department replaced them with GPS collars, data that could be used to assess how oil-field development affects bears and to help identify where they den during the winter—areas that oil companies need to avoid when building winter roads between drill sites.
Even without continuous video, the researchers said the cameras can record up to 17 hours and capture structured clips through the seasons. In spring and summer, the collars recorded short videos of four to six seconds every 10 minutes, while in fall the team used a tighter schedule—every five minutes during daylight as darkness approached.
In addition to footage of feeding and resting, the cameras recorded interactions with other animals, including an encounter between a bear and a pack of wolves after the bear emerged from hibernation in May. Vincent said there was no adverse interaction over food, and she described the exchange as peaceful: “I think they both decided that it wasn’t worth it, so they just looked at each other, then moved on.”
The researchers said the study will continue for another two years, with plans to add collars to 24 more bears to expand the dataset and further test questions about how the population persists on the North Slope.